In general, to seal a device using a thin film, a multi layer encapsulated film is manufactured by alternately laminating organic and inorganic materials on the device. FIG. 1 shows the construction of a multi layer encapsulated film that is manufactured by alternately laminating a planarizing organic thin film and an inorganic thin film according to the related art. FIG. 2 shows the construction of a multi layer encapsulated film that is manufactured by alternately laminating a conformal organic thin film and an inorganic thin film.
In case of the multi layer encapsulated film manufactured in this manner, the organic thin film serves to absorb stress and uniformize surface roughness when an inorganic thin film serving as a barrier against oxygen and moisture is formed, such that the inorganic thin film is uniformly formed.
U.S. Pat. No. 6,570,325 discloses a planarizing film that is used as an organic thin film attached to the upper portion of the device. This organic thin film reduces defects in the substrate to improve surface roughness and enables particles on the upper portion of the device to cover the device, thereby improving the characteristics of the inorganic thin film.
As disclosed in U.S. Pat. No. 5,902,641, for example, a liquid monomer is evaporated by a heat source to be then formed on the upper portion of the device, and then subjected to a phase change of the liquid monomer to a solid phase and polymerization by UV curing, thereby manufacturing the planarizing organic thin film.
The planarizing organic thin film can reduce the defects of the substrate to improve surface roughness and can enable the particles to cover the device. However, as shown in FIG. 3, when the device is covered with the particles, the liquid monomer may gravitate to a portion having a comparatively wide surface area, which makes it impossible to uniformly form the planarizing organic thin film. For this reason, when one kind of organic thin film and an inorganic thin film are alternately formed (FIG. 1), as shown in FIG. 3, it may be difficult to control the amount of permeation of moisture and oxygen through the particles.
Meanwhile, unlike the planarizing organic thin film, when a conformal organic thin film is only used, as shown in FIG. 4, satisfactory step coverage is achieved, and thus a satisfactory barrier property is obtained in view of the device or the particles. In this case, however, it may be difficult to prevent the substrate from being scratched and to uniformize the surface roughness. Accordingly, when one kind of organic thin film and an inorganic thin film are alternately formed (FIG. 2), there is a problem in that it is difficult to control the amount of permeation of oxygen and moisture. This problem is caused because a raw material of a liquid phase, a solid-liquid phase, or a solid phase is vaporized during the phase change by a heat source, and a film is formed in a vapor phase on the substrate having mounted thereon the device, thereby forming a conformal organic film.
As described above, the known multi layer encapsulated film that is manufactured by alternately forming either the planarizing organic film or the conformal organic film and the inorganic film at the top of the device (FIGS. 1 and 2) has merits and demerits according to the intrinsic characteristics of the used organic thin film. For this reason, the known multi layer encapsulated film cannot exert a satisfactory device protection function.